Rotational speed control switch



y 10, 1966 L. H. WIGGER 3,250,871

ROTATIONAL SPEED CONTROL SWITCH Filed Dec. 17, 1963 INVENTOR LAWRENCE H- IGGER ATTO RNEY 3,250,871 ROTATIONAL SPEED CONTROL SWITCH Lawrence H. Wigger, Bartlesville, kla., assignor to Cities Service Oil Company, Bartlesville, Okla, a corporation of Delaware Filed Dec. 17, 1963, Ser. No. 331,279 4 Claims. (Cl. 200-61.46)

This invention relates to a rotational speed control switch. More particularly, it relates to a rotational speed control switch which is responsive to changes in the rate of rotation of a rotating member.

In many processes or forms of machinery, an increase or decrease in the rotation rate of a particular part may result in serious damage or loss, or in an undesirable situation which the operator particularly wishes to avoid. Various types of rotational speed switches have been proposed which are responsive to a decrease in the rotation rate of a rotating member. The torque and speed requirements of these switches are such that they cannot be adjusted accurately at low r.p.m. rates. In addition, such switches have not included an overspced feature to protect against an undesired increase in the rotation rate of a rotating member.

Accordingly, it is an object of the present invention to provide a rotational speed control switch responsive to changes in the rate of rotation of a rotating member.

A further object is to provide a rotational speed control switch responsive to an increase or a decrease in the rotation rate of a rotating member.

Another object of the present invention is to provide a rotational speed control switch which is operable over a substantial range of rotation rates.

Another object of this invention is to provide such a switch which will be operable at very low rotation rates such as one or two revolutions per minute.

A further object of the present invention is to provide a rotational speed control switch having a very small tor sional load requirement.

With these and other objects in view, an embodiment of the present invention is described herein with reference 'to the accompanying sheet of drawings in which:

FIGURE 1 is a frontal view of the invention along the center line of rotation of the rotating portion thereof.

FIGURE 2 is a sectional side view along the line 2-2, showing details of the magnetically operated contacts employed as part of the present invention.

In the embodiment of the invention illustrated in FIG- URES 1 and 2, the numeral 1 represents a hollow body in the shape of a toroid which is at least partiallyfilled with liquid 2 by means of liquid filling spout 3. This hollow body may be constructed of any non-magnetic material such as glass, high density polyethylene, aluminum, copper, brass, lucite and similar materials. Any suitable means for attaching hollow body 1 to the rotating member may be employed, such as base plate 4 to which hollow body 1 is cemented or otherwise attached. Base plate 4, in turn, is attached to the end of rotating shaft 5 supported by journal 6. I-Iollow body 1 should be supported in a substantially vertical manner although angular deviations from the vertical line of up to about 35 will not appreciably aflfect the operation of the invention.

Contained within hollow body 1 is a ball 7 constructed of a magnetic material. Ball 7 may be of any size and shape which permits it to move freely within hollow body 1. Generally, however, it is preferable that the cross sectional configuration of the ball be the same as the cross section of the hollow body. Ball 7 may be constructed of any suitable magnetic material, such as iron and alloys thereof, such as steel.

When hollow body 1 rotates, liquid 2, which at least partially fills hollow body 1, serves to force ball 7 in the i United States Patent 0 direction of rotation. This liquid may be any liquid having a viscosity index number of from about 0.5 to about 5.0. Preferably the liquid shall be thermally stable over the range of temperatures expected to be encountered in the practice of the invention. Some suitable liquids are water, methanol, alcohol-glycerine mixtures, petroleum distillates, silicone base liquids and the like.

Positioned near the bottom portion of hollow body 1 is a set of magnetically operated electrical contacts represented in FIGURE 2 generally by the numeral 8. The electrical contacts are supported by supporting bracket 9 which, in turn, is supported by a stationary member 10. Supporting bracket 9, which is constructed of any suitable non-magnetic material, contains slot 11 to permit the adjustable positioning of contacts 8 in relation to hollow body 1. Locking nut 12 is provided to hold contacts 8 in the desired position in slot 11.

Any commercially available electrical contacting means may be employed in this invention, including those employing magnetic, capacitance or inductive operation. These contacts may be enclosed in an air-tight glass envelope to reduce undesired environmental disturbances.

The contacts 8 illustrated in FIGURE 2 are a three reed make-break pipe set of contacts including reeds 13, 14, and 15. Middle reed 14 has a magnet attached to its outer end so that when placed near a magnetically attractive metal, the reed contacts will be opened and closed, making and breaking the contacts which control the actuating control circuit 16.

Hollow body 1 has been described as having the shape ferred for this invention, any enclosed path generated by the rotation of a plane geometric figure about a line in its plane, herein referred to as a tore-shaped body, may be used in the practice of this invention. For example, an enclosed path having a shape corresponding to the figure generated by the rotation of a square about a line in its plane would be suitable and within the scope of this invention.

Operati0n.-As shaft 5 rotates in a clockwise direction, hollow body 1, which is attached to base plate 4, also rotates. Because of the frictional forces acting on the ball from the wall and from liquid 2, ball 7 will tend to be carried in a clockwise direction along with hollow body 1. However, these forces will be resisted by the gravitational forces acting downward on the ball. When the upward The position at which the ball will remain stationary in rotating hollow body 1 depends on the viscosity of the liquid in the hollow body, the frequency of rotation, the density of the ball and the density of the liquid. The height to which the ball will rise in the hollow body is directly proportional to the viscosity of the liquid and the frequency of rotation and inversely proportional to the difference between the density of the ball and the density of the liquid, whose level should at least equal the desired height.

If shaft 5 stops rotating, ball 7 will immediately seek the low point in the hollow body since the upward forces would not be suflicient to balancethe downward force due to the weight of the ball. At the low point in hollow body 1, ball 7, being constructed of a magnetic material, will attract the magnet on reed 14 of contacts 8, thereby opening or closing contacts so as to activate control circuit 16 which reroutes current to an alarm circuit, a motorstop circuit or to some similarly functioning unit. In this way, damage to various machine parts and other undesirable results of a malfunction may be prevented.

Should the rate of rotation of shaft 5 fall below the desired rate, ball 7 will seek some new, lower point in hollow body 1 at which the upward and downward forces balance. By adjusting the position of contacts 8 to various heights up to 90 clockwise from the vertical axis, the cutout position of the invention may be set at'any desired rotation rate. Manual adjustments can be made to offset any inaccuracies in the ability to predict the balls equilibrium position.

If the rate of rotation of shaft becomes too great, ball 7 will be carried around hollow body 1, the force of gravity being insufficient to bring about equilibrium conditions. As ball 7 moves away from its equilibrium position due to the increase in the rate of rotation of hollow body 1, the ball will cease to attract the magnet on reed 14 thereby opening or closing contacts in the same manner as occurs when the ball drops due to a decrease in the rate of rotation.

The torsional load requirement of the present invention is very small and is governed by the weight of the ball and its distance from the rotating axis. Thus, the invention can be accurately operated at rotation rates of as low as about l-2 r.p.m. with torque requirements as low as 0.036 inch ounce. It should be noted that control, at very low rotation rates, can be established by simply increasing the viscosity of the fluid in the hollow body.

The rotational speed control switch described and claimed herein can be used in a wide variety of applica-' tions. For example, such a switch might find application in various forms of farm machinery or as a control device for various machine tools, such as a lathe. A particularly useful application for the present invention resides in its installation on oil volume meters located on storage units where automatic transfer of the fluid is desired. In this application, the invention is used to stop a charge pump in case the fluid volume meter through which it pumps fails to operate or fails to operate at a specific preset rate. A desirable feature of the present in- 'vention is that it serves to energize the control circuitry only when stall-out or over-speed occurs and not every time a quantity of oil passes through the unit.

I It will be understood that various changes in the details and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art I claim:

1. A rotational speed control switch responsive to either an increase or decrease in the rotary speed of a rotating member comprising;

(a) a hollow tore-shaped body filled with a liquid having a viscosity index number of from about 0.5 to 5.0;

(b) means for attaching said hollow body to the rotary member in a substantially vertical manner, saidrotary member capable of operating in a velocity range of from about one to about 100 r.p.m.;

(c) a ball of magnetic material construction contained within the hollow body, said ball being of such size and shape as to allow the ball to move freely within the hollow body when said body is rotated, said ball thereby assuming same position other than the lowest point in the hollow body when said body is rotated, the said position of the ball being that at which the upward force due to the, rate of rotation and the viscosity of the liquid balance the downward force due to the weight and size of the ball;

(d) electrical contacting means adjustably positioned in close proximity to, the lower portion of said hollow body, said contacting means being activated by the movement of the ball due to an increase or decrease in the rate of rotation of the rotating member;

whereby the electrical contacting means may be adapted to actuate a control circuit that controls the rotating member.

2. The apparatus of claim 1 in which the hollow, torethe hollow, tore-shaped body is selected from the group within the principle and scope of the invention as expressed in the appended claims.

References Cited by the Examiner UNITED STATES PATENTS 2;755,349 7/1956 Silvers 200-87 BERNARD A. GILHEANY, Primary Examiner.

BENJAMIN DOBECK, Assistant Examiner. 

1. A ROTATIONAL SPEED CONTROL SWTICH RESPONSIVE TO EITHER IN INCREASE OR DECREASE IN THE ROTARY SPEED OF A ROTATING MEMBER COMPRISING; (A) A HOLLOW TORE-SHAPED BODY FILLED WITH A LIQUID HAVING A VISCOSITY INDEX NUMBER FORM ABOUT 0.5 TO 5,0; (B) MEANS FOR ATTACHING SAID HOLLOW BODY TO THE ROTARY MEMBER IS A SUBSTANTIALLY VERTICAL MANNER, SAID ROTARY MEMBER CAPABLE OF OPERATING IN A VELOCITY RANGE OF FROM ABOUT ONE OF ABOUT 100 R.P.M.; (C) A BALL OF MAGNET MATERIAL CONSTRUCTION CONTAINED WITHIN THE HOLLOW BODY, SAID BALL BEING OF SUCH SIZED AND SHAPE AS TO ALLOW THE BALL TO MOVE FREELY WITHIN THE HOLLOW BODY WHEN SAID BODY IS ROTATED, SAID BALL THEREBY ASSUMING SAME POSITION OTHER THAN THE LOWEST POINT IN THE HOLLOW BODY WHEN SAID BODY IS ROTATED, THE SAID POSITION OF THE BALL BEING THAT AT WHICH THE 